NCLEX Fluid & Electrolyte Practice Questions

15 free NCLEX-RN fluid & electrolytes questions with answers and rationales — perfect for fluid and electrolytes nclex questions practice. Want them as an interactive timed quiz?

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1. A 65-year-old male is admitted with a history of congestive heart failure and presents with edema, shortness of breath, and crackles on auscultation. Which electrolyte imbalance is he most at risk for?
- A. Hyponatremia ✓
- B. Hyperkalemia
- C. Hypocalcemia
- D. Hypermagnesemia
Answer: A. Hyponatremia — Patients with congestive heart failure often experience fluid retention, which can lead to dilutional hyponatremia due to excess fluid diluting serum sodium levels.
2. A 40-year-old female with a history of Crohn's disease is admitted with severe diarrhea. Which of the following is the best indicator of her fluid volume status?
- A. Serum sodium levels
- B. Serum potassium levels
- C. Daily weight measurements ✓
- D. Blood pressure readings
Answer: C. Daily weight measurements — Daily weight measurements are the most reliable indicator of fluid volume status as they reflect changes in total body water more accurately than serum electrolytes or blood pressure.
3. A patient is receiving intravenous (IV) potassium chloride for hypokalemia. Which of the following assessments is the highest priority for the nurse?
- A. Monitor blood pressure hourly
- B. Check the IV site for infiltration ✓
- C. Monitor the patient's respiratory rate
- D. Check the patient's urine output
Answer: B. Check the IV site for infiltration — IV potassium chloride can cause tissue necrosis if it infiltrates the surrounding tissue, making it critical for the nurse to check the IV site frequently.
4. A 75-year-old patient with chronic kidney disease presents with muscle weakness and cardiac arrhythmias. Which electrolyte imbalance should the nurse suspect?
- A. Hypocalcemia
- B. Hypokalemia
- C. Hyperkalemia ✓
- D. Hypernatremia
Answer: C. Hyperkalemia — Chronic kidney disease often leads to hyperkalemia due to the kidneys' inability to excrete potassium effectively, which can cause muscle weakness and cardiac arrhythmias.
5. A patient with a serum calcium level of 7.8 mg/dL is experiencing tetany and muscle cramps. Which of the following interventions should the nurse implement first?
- A. Administer oral calcium supplements
- B. Encourage increased dietary calcium intake
- C. Prepare for seizure precautions
- D. Administer IV calcium gluconate ✓
Answer: D. Administer IV calcium gluconate — IV calcium gluconate is the most rapid and effective treatment for severe hypocalcemia with tetany, which can be life-threatening if not promptly treated.
6. A patient has been prescribed furosemide (Lasix) for fluid overload. Which electrolyte imbalance is the patient most at risk for?
- A. Hypokalemia ✓
- B. Hypercalcemia
- C. Hypermagnesemia
- D. Hyponatremia
Answer: A. Hypokalemia — Furosemide is a loop diuretic that causes increased excretion of potassium, placing the patient at risk for hypokalemia.
7. A patient with severe vomiting is admitted to the hospital. The nurse expects which acid-base imbalance?
- A. Metabolic alkalosis ✓
- B. Respiratory acidosis
- C. Metabolic acidosis
- D. Respiratory alkalosis
Answer: A. Metabolic alkalosis — Severe vomiting leads to loss of stomach acid, resulting in metabolic alkalosis due to increased bicarbonate concentration in the blood.
8. The nurse is caring for a patient who has a serum magnesium level of 1.1 mg/dL. Which of the following symptoms would the nurse expect to find?
- A. Lethargy and confusion
- B. Hyperreflexia and tremors ✓
- C. Decreased deep tendon reflexes
- D. Cardiac arrest
Answer: B. Hyperreflexia and tremors — A low magnesium level can lead to neuromuscular excitability, resulting in symptoms like hyperreflexia and tremors.
9. A patient with diabetic ketoacidosis (DKA) is admitted to the emergency department. Which electrolyte imbalance is most likely to occur in this situation?
- A. Hypokalemia
- B. Hypercalcemia
- C. Hyperkalemia ✓
- D. Hyponatremia
Answer: C. Hyperkalemia — In DKA, insulin deficiency leads to potassium shifting out of cells into the bloodstream, often resulting in hyperkalemia.
10. A 50-year-old patient presents with confusion, headache, and lethargy. Laboratory results show a sodium level of 120 mEq/L. What is the most appropriate initial treatment?
- A. Administer normal saline IV
- B. Restrict fluid intake
- C. Administer hypertonic saline IV ✓
- D. Encourage oral sodium intake
Answer: C. Administer hypertonic saline IV — Severe symptomatic hyponatremia requires prompt treatment with hypertonic saline to rapidly increase serum sodium levels and prevent neurological damage.
11. A patient with a serum potassium level of 6.5 mEq/L is being treated for hyperkalemia. What is the most critical intervention?
- A. Monitor the patient's heart rhythm ✓
- B. Administer oral sodium polystyrene sulfonate
- C. Encourage increased fluid intake
- D. Administer diuretics
Answer: A. Monitor the patient's heart rhythm — Hyperkalemia can cause life-threatening cardiac arrhythmias, making continuous cardiac monitoring essential.
12. A patient with a history of alcoholism is admitted with a serum magnesium level of 0.9 mg/dL. Which of the following interventions is the highest priority?
- A. Administer oral magnesium supplements
- B. Initiate seizure precautions
- C. Encourage dietary intake of magnesium
- D. Administer IV magnesium sulfate ✓
Answer: D. Administer IV magnesium sulfate — Severely low magnesium levels can lead to cardiac and neurological complications, requiring prompt correction with IV magnesium sulfate.
13. A patient is receiving IV fluid therapy with 0.9% sodium chloride. The nurse observes swelling at the IV site. What should the nurse do first?
- A. Apply a warm compress to the site
- B. Stop the IV infusion immediately ✓
- C. Elevate the affected limb
- D. Check for blood return in the IV line
Answer: B. Stop the IV infusion immediately — Swelling at the IV site indicates possible infiltration, and the priority is to stop the infusion to prevent further tissue damage.
14. A patient has been prescribed spironolactone for hypertension. Which electrolyte imbalance should the nurse monitor for?
- A. Hypokalemia
- B. Hyperkalemia ✓
- C. Hyponatremia
- D. Hypercalcemia
Answer: B. Hyperkalemia — Spironolactone is a potassium-sparing diuretic, which can lead to an increase in potassium levels, resulting in hyperkalemia.
15. A patient with severe dehydration is receiving lactated Ringer's solution. The nurse knows this solution is primarily used to treat which condition?
- A. Hyponatremia
- B. Hypokalemia
- C. Metabolic acidosis ✓
- D. Metabolic alkalosis
Answer: C. Metabolic acidosis — Lactated Ringer's solution contains lactate, which is metabolized to bicarbonate in the liver, helping to correct metabolic acidosis.

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